I've tried to summarise the important differences between the various
proposals on the wiki page, but it still needs lots of illustrative
examples. Anyone who is interested, please contribute!
Barney.
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amazed myself, and expect bug reports!-).
i've also added the three language and implementation
features i consider most important to make library-based
extensible records useable in practice (none of which
happen to be specific to records, btw;-).
in trying to be comprehensive (mostly to
| There seems to be widespread agreement that the current situation wrt
| records is unacceptable, but the official GHC policy is that there are too
| many good ideas to choose from - so nothing gets done! I hence humbly
| propose that [http://www.cs.uu.nl/~daan/download/papers/scopedlabels.pdf
Bulat Ziganshin wrote:
> i propose to start "Records project" by composing list of
> requirements/applications to fulfill; we can keep it on Wiki page.
Wiki page duly created
http://hackage.haskell.org/trac/ghc/wiki/ExtensibleRecords
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the
context 'a\opt1'). The type we want should say that 'opts' cannot
have any fields except 'opt1' (though that is optional). Flex cannot
express this type.
ok, then i misunderstood what you wanted to demonstrate with
that example. but then this part does
Hugs.Trex> :t let f opts x = (opt1="default"|opts) in f
let {...} in f :: a\opt1 => Rec a -> b -> Rec (opt1 :: [Char] | a)
This completely loses the aim of optional arguments: with this type,
the argument 'opts' cannot have a field 'opt1' (as shown by the
context 'a\opt1'). The type we want
Whatever system GHC settles on
is almost certain to become part of the Haskell standard, and this
particular system has some deep limitations which could not be got
round without ripping it all out and starting again.
i'd like to have "extensible records", but i'd rath
On Sun, Nov 11, 2007 at 03:02:56PM +0300, Bulat Ziganshin wrote:
> Hello Barney,
>
> Sunday, November 11, 2007, 2:34:14 PM, you wrote:
> > An important application which is made impossible by this approach is
>
> i propose to start "Records project" by composing list of
> requirements/application
On Sat, Nov 10, 2007 at 11:24:24PM +, Voldermort wrote:
>
> I assume that porting an existing implementation would
> be much easier than starting from scratch.
I doubt this is true, but even if it is I would prefer to see features
chosen based on their merits.
(I'm not familiar with the vari
Hello Barney,
Sunday, November 11, 2007, 2:34:14 PM, you wrote:
> An important application which is made impossible by this approach is
i propose to start "Records project" by composing list of
requirements/applications to fulfill; we can keep it on Wiki page.
this will create base for language t
I think this would be a BIG mistake. Whatever system GHC settles on
is almost certain to become part of the Haskell standard, and this
particular system has some deep limitations which could not be got
round without ripping it all out and starting again.
The problem with this (and other "Fl
I've entered a feature request for this on Trac
http://hackage.haskell.org/trac/ghc/ticket/1866
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Hello Stefan,
Sunday, November 11, 2007, 2:54:51 AM, you wrote:
>> Is there any chance of seeing extensible records in GHC 6.10?
> I second this request
+1
--
Best regards,
Bulatmailto:[EMAIL PROTECTED]
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I misread it as 6.1. Sorry about that.
-Original Message-
From: Stefan O'Rear [mailto:[EMAIL PROTECTED]
Sent: Saturday, November 10, 2007 6:55 PM
To: Seth Kurtzberg
Cc: 'Voldermort'; glasgow-haskell-users@haskell.org
Subject: Re: Extensible Records
On Sat, Nov 10, 200
On Sat, Nov 10, 2007 at 06:35:34PM -0500, Seth Kurtzberg wrote:
> Is there any chance of seeing extensible records in GHC 6.10? There seems to
> be widespread agreement that the current
> situation is unacceptable, but the official GHC policy is that there are too
> many good ideas to
On Sat, Nov 10, 2007 at 06:35:34PM -0500, Seth Kurtzberg wrote:
> 6.10? I think that's a typo as the current version is 6.8.1. Or did I
> misunderstand what you were saying?
6.8.1 is released, there is abolutely no way new features are going to
enter a published version. Hence, 6.10.
Stefan
s
ECTED] On Behalf Of Voldermort
Sent: Saturday, November 10, 2007 6:24 PM
To: glasgow-haskell-users@haskell.org
Subject: Extensible Records
Is there any chance of seeing extensible records in GHC 6.10? There seems to
be widespread agreement that the current
situation is unacceptable, but the officia
Is there any chance of seeing extensible records in GHC 6.10? There seems to be widespread agreement that the current
situation is unacceptable, but the official GHC policy is that there are too many good ideas to choose from - so nothing
gets done! I hence humble propose that http
> Is the feature described in the paper just a
> proposal or is there a switch somethere to enable
> it?
I think you used the wrong compiler. It's called Hugs :-)
Prelude> #a ( a='a', b=True )
ERROR - Trex.insertField not in scope
*** Possible cause: "Trex" module not imported
Prelude> :l Trex
No, extensible records are not implemented in GHC. Hugs (or some
variant of it) implements TRex, another extensible record variant. The
problem is that the record design space is large, and seems to lack
local optima. And all reasonable variants break backward compatibility.
As a result
I feel like I have way too much code of the form:
changeGpart (C a b c d e f g h i) g' =
C a b c d e f g' h i
So, I got excited reading Simon and Mark's
"Lightweight Extensible Records For Haskell" paper
as a way to get rid of this cruft. I immediately
star
Are you sure extensible records are needed, I used to really want them
until I developed some idioms which seem to replace most needs for them.
(1) Haskell Records
just plain old haskell records can be used in an extensible fashion
quite easily, just provide an alternate to the constructor which
I just read your proposal for "lightweight extensible records for
Haskell" and find it great.
But I just wonder : why not keeping both records systems (Haskell 98 and
extensible) with their own syntax, introducing for example [{..}] for
extensible records for example. This wou
Thanks, have read the paper, however also saw the paper by Simon
Peyton-Jones and
Mark Jones on Lightweight Extensible Records for Haskell, which I think
Simon refered
to in an earlier post... would it not be better to have this instead?
Regards,
Keean Schupke.
Alastair Reid wrote
On Wednesday 06 November 2002 10:48 pm, Nicolas Oury wrote:
> I am going to try to persuade you:
>
> * first of all, it seems to be needed in order to make "first class
> modules" (cf your paper) . And I think that a true module system would
> be useful. But I may be wrong.
>
> * As far as I am co
t is easy to understand, safe and avoid to rename
with different names some fields that should have the same name.
* ...
I could try find other reasons tomorrow.
Simon
| -Original Message-
| From: Nicolas Oury [mailto:Nicolas.Oury@;ens-lyon.fr]
| Sent: 06 November 2002 08:38
| To: [EMAIL P
> Just a quick point, which I'm sure you realise, but static typing
> gives you guarantees about the runnability of a program that dynamic
> typing breaks...
Which, presumably, is why he wants T-Rex which gives strong typing and
extensible records and comes from the same great so
re is less
> chance of making an error.
I'm not sure I get you but I was thinking of staticly typed extensible
records, like in T-Rex.
In fact, I need less than that. I think that not declared records, like in
SML are sufficient for me.
Best regards,
Nicolas
>
> Regard
wrote:
> > Hello, is there something like extensible records in ghc?
>Are you wanting something like Hugs' T-Rex or did you have something
>else in mind?
Hello,
For what I understand of T-Rex it is what I wait.
I need something that can allow to use records without declaring thei
ded otherwise.
Simon
| -Original Message-
| From: Nicolas Oury [mailto:Nicolas.Oury@;ens-lyon.fr]
| Sent: 06 November 2002 08:38
| To: [EMAIL PROTECTED]
| Subject: Re : Extensible records in Haskell
|
| > > Hello, is there something like extensible records in ghc?
|
| >Are you w
> > Hello, is there something like extensible records in ghc?
>Are you wanting something like Hugs' T-Rex or did you have something
>else in mind?
Hello,
For what I understand of T-Rex it is what I wait.
I need something that can allow to use records without declaring thei
> Hello, is there something like extensible records in ghc?
Are you wanting something like Hugs' T-Rex or did you have something
else in mind?
--
Alastair Reid [EMAIL PROTECTED]
Reid Consulting (UK) Limited http://www.reid-consulting-uk.ltd.uk/
Hello,
is there something like extensible records in ghc?
Is it planed to?
Can anyone help?
Best regards,
Nicolas Oury
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